Generally, austenite stainless steel exhibits relatively good corrosion resistance. However, it is vulnerable to pitting in an aqueous solution containing Cl group, and is vulnerable to wear due to relatively low hardness. Particularly, there is a limit as to apply it in seawater conditions.
Therefore, in order to solve such a problem, various surface modification methods have conventionally been accomplished to achieve nitriding and carburizing.
However, when the nitriding and carburizing processes are accomplished at a high temperature (a salt bath nitriding process, a high temperature carburizing process, etc), nitrides and carbides are precipitated and corrosion resistance is lowered.
Further, when the nitriding and carburizing processes are accomplished at a low temperature condition, there is a problem that it is difficult to form a carburizing and nitriding layer due to a natural oxide film existing on the surface of a metal.
Therefore, a method for solving such problems is required.